The conventional positioning device for electric discharge machining or cutting work achieves the high precision positioning by an electrical contact sensing method between a work piece and an electrode or tool, using the conductivity of the work piece or tool electrode (e.g., refer to patent document 1).
Also, a method for measuring the residual cutting amount of material accurately and safely, using a long distance measurement laser displacement sensor, without making direct contact with the material and with a sufficient distance between the material and the tool left, was established (e.g., refer to patent document 2).
Moreover, there was established a positioning method for positioning a table by driving a drive mechanism, based on the detection result of the rough feed amount in a first position detection sensor and the detection result of the minute feed amount in a second position detection sensor, in which the first position detection sensor detects the rough feed amount of the table on which the work piece is laid and the second position detection sensor detects the minute feed amount (e.g., refer to patent document 3).
Patent document 1: JP-A-2003-205439 (FIG. 2)
Patent document 2: JP-A-2000-52198
Patent document 3: JP-A-63-109956